The team at 99U follows productivity trends on a daily basis and noticed that every few years, a research study comes along that fundamentally changes the way we think about work. These studies are often conducted over decades and follow people across their careers to offer the rest of us a template to follow for our day-to-day lives. Below are three studies that are behind much of the productivity and creativity advice you read every day.

The Marshmallow Test

In this landmark 1972 study of delayed gratification, Stanford researchers selected a group of children and offered them a deal: the child could be given a single marshmallow immediately or, if they chose to wait 15 minutes, they would be rewarded with two marshmallows.

The 10,000 Hours Rule

And not just any practice, deliberate practice. Top performers select the difficult aspects of their work and repeat them endlessly until they are ingrained as habit. Think of Shaquille O'Neal practicing his free throws—his weak point—rather than practicing slam dunks.

The Grit Scale Indicator

Angela Duckworth of the University of Pennsylvania and Christopher Peterson of the University of Michigan took the Stanford Marshmallow test to the next level. In 2007, they developed a test that would measure a person's "grit," that is, an unassailable desire to see a goal or project through to the end. The test asked participants to read questions like "I have achieved a goal that took years of work" and rate its truthfulness on a five point scale.

Those who were shown to have more "grit" outperformed their less gritty peers. High grit scores correlated to higher GPAs, spelling bee winners, and West Point graduates.

Whenever a new theory on productivity and work emerges, you can bet it has origins in studies like these. Luckily, writers and journalists comb through the science journals so you don't have to. While studies will never replace the observations we get from our day to day lives, keep an ear out and see if they can inspire small tweaks or changes to your workday.